The present invention relates generally to the field of computed tomography scanning systems and more particularly to thermal management of circuits used in such computed tomography systems.
Generally, a computed tomography (CT) scanning system for acquiring and processing image data of an object of interest, for example a human patient, includes a source of X-ray radiation, typically an X-ray tube. Operationally, the X-ray radiation source projects the X-ray beam towards the object being imaged and further towards a detector array made up of a plurality of detector assemblies. The detector assemblies detect the X-ray radiation after passing through or around the object, and subsequently convert this X-ray radiation to a plurality of electrical signals that represent the intensity of the incident X-ray radiation. These electrical signals are acquired and processed further to construct an image of the features within the object. A rotational system, typically including a gantry fixedly attached to the X-ray source and the detector array, enables them to rotate at least one full 360° turn around the object.
Operationally, as the X-ray radiation source and the detector array fixedly attached to the gantry rotate, an integrated circuit array, such as a data acquisition system (DAS) circuit or chip array, having a plurality of integrated circuits, such as, data acquisition chips mounted on the printed circuit board of the detector assembly, collect data corresponding to electrical signals representing attenuation of the X-ray radiation after passing through or around the object. During operation, thermal energy is generated by the data acquisition chips as they are powered to complete their processing functions. A particular challenge in such systems, then, arises from the need to remove this energy from the chips and, to the extent possible, to maintain the chips in a relatively isothermal condition (i.e. reduce the temperature variation between separate chips or processing circuits).
Generally, in conventional approaches the thermal load generated from the data acquisition chip array of a conventional CT scanning system is mitigated through an air circulating system that blows air over the data acquisition chips. This method of cooling may not have the capability to maintain the data acquisition chips in an isothermal condition and significant variation in temperature may be observed between the data acquisition chips. Variation of temperature in the data acquisition chips is also observed during the transient phases when the CT system is rotating or in a stationary position. Moreover, in improved CT scanning systems the width of the detector assembly building the detector array is larger and more densely populated as compared to conventional CT scanning systems in order to accommodate wider array of axial coverage of the patient. Therefore, the thermal load generated from the data acquisition chip array of the detector assembly of such improved CT scanning systems is relatively higher than the heat load generated from conventional CT systems.
There is a need, therefore, for a thermal management system suitable to handle this additional heat load and to reduce the variation in the temperature of the data acquisition chips of the detector assembly of a CT system is desirable.